Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

[mansaxel]

A good bag. That seems like a very low price. HP kit of that era was beautifully made.

Indeed it is. Jammy git territory, providing it works. Best part is it was in-country, so shipping included it still barely reached £60.

Function generators with any degree of sophistication, (at least sweep) and respectable waveforms, I've found are incredibly useful. I've got a Siglent SDG2000X I use a lot.

Yes, I've seen what the one included in a R&S scope can do, which is really nice, and I suppose one can do similar shenanigans with this, albeit analog only trickery.

[tggzzz]

Playing with a Function gen with modulation is a bit magical and great fun!
Make sure to have an audio-filter (simple RC LPF is good enough in a pinch) handy,
so you can test-drive the sweep capability as well.

Now, how to observe FM and AM modulation?

My favourite is to build a high Q N-path bandpass filter, with N=8 for AM and N=4 or 8 for FM. (High Q? Anything above 1000, using 10% capacitors and resistors. Let's say 10kHz centre frequency with a 10Hz bandwidth.

Unmodulated with N+8 is a beautiful up and down staircase. Change the frequency by 1Hz, and watch the escalator move one way or the other depending on whether the frequency is above/below the centre frequency. Change the frequency a bit more (than +-5Hz), and watch the amplitude drop off at 100dB/decade or so.

AM modulated at the centre frequency is as you would expect, provided the amplitude modulation frequency is <5Hz.

Now connect a scope X to one capacitor, and the Y to the next capacitor (N=4) or next but one capacitor (N=8), i.e. the I and Q capacitors. With the unmodulated input at the centre frequency, the scope will show a single point.

With the input slightly off the centre frequency, the point will move in circle clockwise or anticlockwise depending on whether the frequency is above/below the centre frequency. Add some AM, and the circle will become a torus. Add triangular wave FM, and the point will circle in one direction, then the other.

And if that doesn't explain modern receivers, nothing will.

[Zenith]

HP function generators are mentioned here.

https://www.hpmemoryproject.org/wb_page ... ge_10c.htm

The 3312A is featured in the March 1975 Hewlett-Packard Journal.

http://hparchive.com/Journals/HPJ-1975-03.pdf

50 years ago, when it was released, it would have been a top end and very expensive bit of kit.

These days with the vast improvements in digital electronics, particularly DDS, definitely dated but still useful. Being analogue isn't all bad. Modern DDS AWGs can produce a lot of RFI, especially the cheap ones.

Anyway, it's a thing of beauty and a nice thing to own, and I'm sure it will be useful as well.

[tggzzz]

These days with the vast improvements in digital electronics, particularly DDS, definitely dated but still useful. Being analogue isn't all bad. Modern DDS AWGs can produce a lot of RFI, especially the cheap ones.

35 years ago, an HP DDS was classed as a munition. Export control is nothing new!

[mnementh]

Next Act of my HP 85A Resurrection Opera is up here: viewtopic.php?p=8408#p8408

Enjoy!!!

mnem
or don't. that's really as much what you bring to the experience as what I've presented...

[bd139]

Another major goalpost in my acquisition plan has been reached. [(hp)] 3312A, Israeli tank brake block past (also some productive past at a radar manufacturer in the same country) -- bough BIN for 400SEK on local auction site. It did not linger more than a few minutes on the site before I pounced.

Some violence from the sejour past its working life, there's a dent in the front panel, but insides look clean, all controls operate nicely, and there are 4 feet, 2 front ones with wire bail. Missing is one or two of the pot knob heads, but that is not a major issue for me. The top lid's been off. It was sticky, and required brushing with detergent and some magic sponge rubbing to clean up. This revealed some faint felt tip pen traces that I will ignore.

Not yet tried to power it on, but that will come today.

99% of the cancer in those can be cured by cleaning the modular switches at the top of the front panel. I've had 3 and none of them had any issues apart from that

[mansaxel]

Not yet tried to power it on, but that will come today.

99% of the cancer in those can be cured by cleaning the modular switches at the top of the front panel. I've had 3 and none of them had any issues apart from that

It works, as far as I can tell. A bit of strange behaviour in the modulation section, but that might be down to cleaning switches issues. I'm playing with the ScopeMeter as verification, so probably should set the B channel input on that as trig source and take the sync out on to there.

[mansaxel]

It works, as far as I can tell. A bit of strange behaviour in the modulation section, but that might be down to cleaning switches issues. I'm playing with the ScopeMeter as verification, so probably should set the B channel input on that as trig source and take the sync out on to there.

Yeah, it mostly works. Took the modulation output, not the sync out, into the B channel of the ScopeMeter, and trigged on that, and now it looks like it's supposed to.

Of note is that the sine is distorted (as in skewed) at extreme low end of the frequency control. Can be fixed in all but one case by switching decade and adjusting the frequency control to 10x the value. The manual talks about this in terms of frequency accuracy; it suggests being at "10" is better than being at "1" on the variable control and that going to a lower decade thus is preferential.

[Zenith]

I often wonder how well some TE worked when it left the factory, and whether when you check it out with modern TE you are putting it to a very harsh test, or you do indeed see faults that are the result of 40 years plus of ageing. I somehow doubt that this would have shown the severe sinewave distortion you describe when it left the factory.

Apart from cleaning switch contacts, which clears a lot of faults, I wonder if the triangle generator isn't working properly at the lowest frequencies, or whether there's a problem with the triangle to sine circuitry, possibly caused by component drift.

[25 CPS]

Seems a shame to just abandon it, when I have its brother on the shelf, also collecting dust.

Is there any way to get it tooya without customs raping you on it as if it were a working gazillion-dollar meter?


mnem
yes, you may touch it.

Ah it's ok. If nothing else, it's a printed copy of the manual and spares for my other Simpson 635 and 260s. But wow, this is the worst case of battery corrision I've ever seen. I've never come across a situation where the mess has gotten out of the battery compartment and spread across the outside of the casing like that.

[AVGresponding]

PSA for UK ebay users:

Warning to be aware of a UK ebay seller by the name of jules18999

They listed a parts only Fluke 8125A for £60 BIN + £15 shipping, which is upper end but not top price. After a little umming and ahhing, I bought it.

A few minutes later I saw they listed another one, also parts only, for £400, which is way over the odds. Naturally my spidey senses start tingling at this, and sure enough, a short while later I got a message from the seller:

"Hi xxxxx, there’s been an error in the listing, my daughter made a mistake and listed the wrong item.
I paid far more for the item she listed, really sorry and would you accept a refund in full?"

To which I replied:
"Dear xxxxx,
While I can't stop you from cancelling the sale, I made the purchase in good faith, and I have to say, at the market price for these items, when they are "parts only".
As far as I am concerned, the ball is firmly in your court at this point."

They replied:
"Hi xxxxx , the mistake was made in good faith and I have never ever cancelled a sale before.
Im not happy about having to do this but i have to provide for my family and things are very hard at the moment.
Best regards."

They subsequently cancelled the sale using the reason "out of stock". I've given them the feedback they deserve on ebay, and am waiting to see if they relist it.

[25 CPS]

I'm not sure whether to go bad news first or last.

I guess good news first. I did have some test equipment fun at home the other day. I saw the Gary Ramsey video of the Hewlett Packard 3325A function generator that had spurious non-harmonically related content in the output which he examined using a 3585A spectrum analyzer. I have a 3325A as well and had never checked the quality of the output in the frequency domain other than doing a THD+N measurment on it using the 8903B audio analyzer a few years ago so I prepared a similar test setup to his.







The HP 3588A spectrum analyzer that I have is a slightly newer spectrum analyzer of similar capability to the 3585A that Gary Ramsey used, and I did a similar setup with 0 dBm at 1 MHz out of the 3325A into the spectrum analyzer but also passed through a T to a Tektronix TAS 485 scope in order to view waveform.





Luckily, there were no spurious emissions sticking up out of the noise floor and the second and third harmonics were well below the -40 dBc specified for the 200 kHz to 2 MHz range. The 3325A was a $75 Canadian eBay purchase that I arranged to pick up in person to avoid shipping costs and damage so seeing it performing objectively well made me very happy.

Now for the not-happy bad news. Several of us at work were talking about a technical problem and I offhand mentioned that an Audio Precision test set might be a useful tool for investigating it. That's when the manager said he'd thrown out a bunch of Audio Precision Portable One and Portable One Dual Domain test sets. I'm lost for words in so many different ways there.

[mnementh]

mnem
*dies a little inside*

[25 CPS]

I consoled myself about the direct-to-dumpster policy for writing off old test equipment with a Facebook Marketplace purchase a couple of days ago from a lady who it turns out works in the next building. We met for coffee and shot the breeze and I came away with another Simpson 260 and an Amprobe clamp. Do I really need another Simpson 260? No. Do I enjoy them, yes.

I was about to begin checking them out this afternoon when I got downstairs and discovered that air conditioner condensation had run all over the floor by the furnace. That put a stop to doing anything on the bench. I traced the drain line and it wasn't plugged, right up to the ductwork sheetmetal above the furnace where it was dripping out onto the floor. Obviously the blockage was inside so I shut it all off, got out some screwdrivers and took the sheet metal panel on the front that acts as an access hatch off - and discovered the evaporator coils all covered in ice and the ice was blocking the drain tube. Power switched back on, clean up the immediate mess, and let it run on fan only to blow ambient temperature air over the ice to melt it. This freed up the drain tube and water began pouring down it as all the ice melted. While that was taking place, I gave the meters a very cursory checkover in between a couple of phone calls with a friend of mine who works in HVAC.





The mirror on the 260's scale has largely disappeared. You can see part of it at one edge where it's slid down inside. But I checked a couple of ranges and AC and DC volts work even if they read a bit low and the meter movement is free, so it's off to a better start than that 635 that turned out to have severe battery corrosion. I have a 270 that's also a bit off. I may attempt a calibration on one or both of them. It'd be a good excuse to build a 50 uA current source.



I originally saw and responded to the 260 listing and totally missed the Amprobe. I have another Amprobe that I never did anything with. They both came with test leads but I couldn't figure out how to hook them up to the terminals on the bottom and that kind of discouraged me. Anyways, I'd taken the subway out to meet that HVAC friend of mine after work the day of the pickup and he was finishing up a job with two other guys and while I was showing them the meters, it suddenly dawned on me how the lead connections twist and lock into place on the Amprobes. It's obvious once you realize how they intend it to work. Anyways, I did a quick volts test on these off the tube filament output on the Elenco power supply that famously smoked when I was testing another meter. There is no volts range on the Amprobes that is low enough to show much deflection on the 16 volts the filament windings on the transformer throw off and it was a bit difficult getting a good picture showing the scale but you can see it's up about where it should be. Interestingly, the volts function on both Amprobes seem to work fine on AC and DC. I have to admit not knowing much about these meters and Amprobe doesn't seem to come much at all, if ever in vintage test equipment discussion - definitely nowhere near as often as the usual trifecta of Simpson/Triplett/AVO.

I didn't set up a current test jig to try out the two Amprobe meters as current clamps, which is their main function. That's going to have to wait for later. The air conditioner mess needs to be dealt with. The AC itself doesn't seem to be working efficiently, so it's probably leaked refrigerant off. Then there's the partially cleaned up mess on the floor. I cleaned up the water that pooled but two boxes got wet on the bottom and some other wet spots are going to have to air dry. Nothing inside appears to have been damaged but I need to empty them out and organize the contents and throw out the soggy cardboard. It's one thing after another, I swear.

[Zenith]

I consoled myself about the direct-to-dumpster policy for writing off old test equipment.......

Frustrating, wasteful and silly. I worked in a place where one of the managers was obsessive-compulsive tidy, a clear desk policy and all the rest. In fact he suffered from OCD. A bona fide nutcase. He couldn't stand any clutter at all. There were a load of Racal stat muxes, which the immediate need for had passed. He hired a skip (dumpster) and filled it with all sorts of things which didn't need to be thrown away. The stat muxes were on top. Someone saw them and his eyes popped out. He rescued them and sold them for £700 within a few days. This was 35 years ago, so in modern money, a lot more. They sometimes had to buy new items after he'd decided to throw out perfectly good ones. Then there was his super secure computer room containing nothing but a high end UNIX workstation, (at the time eye wateringly expensive), which was used for nothing and which he knew nothing about. It must have been a sort of trophy. Anyone's contactless pass would give entry, and that's how it was discovered it was used for absolutely nothing. He'd overlooked having the entry system reconfigured.

At least Simpson meters are small and fairly inexpensive. You might have had a thing for HP VNAs or similar - think hernia risk and floor loading problems.

[nixiefreqq]

I was about to begin checking them out this afternoon when I got downstairs and discovered that air conditioner condensation had run all over the floor by the furnace. That put a stop to doing anything on the bench. I traced the drain line and it wasn't plugged, right up to the ductwork sheetmetal above the furnace where it was dripping out onto the floor. Obviously the blockage was inside so I shut it all off, got out some screwdrivers and took the sheet metal panel on the front that acts as an access hatch off - and discovered the evaporator coils all covered in ice and the ice was blocking the drain tube. Power switched back on, clean up the immediate mess, and let it run on fan only to blow ambient temperature air over the ice to melt it. This freed up the drain tube and water began pouring down it as all the ice melted. While that was taking place, I gave the meters a very cursory checkover in between a couple of phone calls with a friend of mine who works in HVAC.

just went thru the same thing with my A/C. icing due to a slow refrigerant leak that they have been trying to find for about 4 years.

used to cost me $65 a pound for R410. but according to the maintenance manager at my local A/C shop, the government just mandated that R410 must be replaced with a more environmentally friendly refrigerant and can no longer be produced.

so the 2 lbs they put into my system cost me $195 each. holy crap! almost 400 bucks for a top up! (and they still can't find the leak).

looks like it will mean a total system replacement. am trying to delay this because according to the manager new systems are still shipping with the obsolete R410 and units with the new chemical will not be available until oct or nov. wtf?

[tggzzz]

At least Simpson meters are small and fairly inexpensive. You might have had a thing for HP VNAs or similar - think hernia risk and floor loading problems.

And yet you were considering a 35kg Fluke calibrator. Still only £108

[Zenith]

At least Simpson meters are small and fairly inexpensive. You might have had a thing for HP VNAs or similar - think hernia risk and floor loading problems.

And yet you were considering a 35kg Fluke calibrator. Still only £108

Very lazily and for a much lower price - a fiver - if it was local.

They say that one doesn't work.

[tggzzz]

At least Simpson meters are small and fairly inexpensive. You might have had a thing for HP VNAs or similar - think hernia risk and floor loading problems.

And yet you were considering a 35kg Fluke calibrator. Still only £108

Very lazily and for a much lower price - a fiver - if it was local.

They say that one doesn't work.

Take your chances on a desoldering rape opportunity?...

I have a 3-piece Datron calibrator that I really ought to get to work. Trouble is that not only is there no service manual, there is no operators manual - and it really needs that.

Piece 1 is a 1kV PSU and controller, not working.

Piece 2 is a KVD, full of ~200 matched VH202C foil resistors. Equivalent new price is ~£30 each There's a chain of them for the voltage divider, plus a chain of them to guard the voltage divider. No expense spared!

Piece 3 is a "calibration bridge / lead compensator". Not much concept of what that is nor how to twiddle the 9 pots. (More VHP102s inside )

Pieces 1 and 3 are connected with a spiders web of PTFE leads between uninsulated 4mm binding posts. Interconnections look understandable, but that's unproven.

Pieces 2 and 3 ought to be interconnected, but aren't, and I doubt I'll ever figure out how.

Fault is that the PSU comes on and works a bit, but locks up when attempting to turn on the output.

[Zenith]

TE with no manual is always a dubious prospect.

It might have a problem you can fix without a manual or cct diagram, such as a loose connection or dirty contact.

The manual might turn up after a time on one of the usual sites, ebay, or at a swapmeet.

You might find the unit is a rebadged version of something that does have a manual.

It might be there's a similar item with a manual from the same maker, and that's close enough.

I take the view that TE with no manual is worth next to nothing. There may be recoverable parts, such as frequency standards which are worth having. If you tinker things together, junk TE can give a nice case, IEC connector and switch, and maybe a transformer. If you had to buy that new, it would be damned expensive.

Some things, such as Panasonic scopes, are notorious for there being no documentation.

Some items I've only bought because the service manual was included. Just as well, because the instrument is obscure and the manual unobtainable.

I really don't know about that Fluke calibrator, but I suspect it's a £108 doorstop. There's something odd about the price of this and the £10s of thousands asked for a used, working one.

[tautech]

I have a 3-piece Datron calibrator that I really ought to get to work.

While likely not the same model there may be some tips in Defpoms Datron repair series:
https://www.youtube.com/playlist?list=P ... QJR3OgwElR

[tggzzz]

TE with no manual is always a dubious prospect.

It might have a problem you can fix without a manual or cct diagram, such as a loose connection or dirty contact.

Even simpler, the exposed 1kV connections might be wrong.

Embiggen the picture below. Yes, that is a 19" 9U rack

Not sure what the "Null Detector" cable should be connected to; almost certainly one of the sets of terminals on the bottom piece. But then what's the "Bridge Power 200V max" on the left hand 4mm binding posts?

OTOH it would be easy to find a source for the "Reference Input". The big hint is that the key switch allows you to select 10V or 1.018V.

The manual might turn up after a time on one of the usual sites, ebay, or at a swapmeet.

Highly unlikely; there hasn't been anything related to these on fleabay in years. I've heard of one copy of a manual, but that owner wouldn't release it since his source was "illegal", whatever that means.

You might find the unit is a rebadged version of something that does have a manual.

It might be there's a similar item with a manual from the same maker, and that's close enough.

That's the best hope. Unfortunately all the "more modern" calibrators have all the pieces wired together correctly inside the box, with software twiddling all the knobs.

I take the view that TE with no manual is worth next to nothing. There may be recoverable parts, such as frequency standards which are worth having. If you tinker things together, junk TE can give a nice case, IEC connector and switch, and maybe a transformer. If you had to buy that new, it would be damned expensive.

The KVD was almost certainly salvageable; I didn't realise how many salvageable components were in that piece alone! I could almost certainly sell that for more than I paid for the whole lot.

The "worth" would never have been more than entertainment. Unfortunately I've yet to work up the courage to be entertained by 1kV where it shouldn't be.

Some things, such as Panasonic scopes, are notorious for there being no documentation.

Some items I've only bought because the service manual was included. Just as well, because the instrument is obscure and the manual unobtainable.

I really don't know about that Fluke calibrator, but I suspect it's a £108 doorstop. There's something odd about the price of this and the £10s of thousands asked for a used, working one.

These are nothing without the calibration certificate, since they are calibrators themselves. Not sure where you would go to get this calibrated; probably NPL or PTB in Germany. PTB have been known to turn up at Makerfaires and allow you to connect your stuff to their equipment. I took a voltage source and measured it with an HP3458 that they had calibrated the day before Not sure they would allow you to do a full calibration of this though, even if I could carry it there

Mine is the kind of thing that only very serious metrology labs would have, the best available until Josephson Junctions came along. 4.5 digit calibrators are mere toys by comparison.

[tggzzz]

I have a 3-piece Datron calibrator that I really ought to get to work.

While likely not the same model there may be some tips in Defpoms Datron repair series:
https://www.youtube.com/playlist?list=P ... QJR3OgwElR

Oooh. That's recent. I'll have to look.

Thanks

[25 CPS]

Frustrating, wasteful and silly. I worked in a place where one of the managers was obsessive-compulsive tidy, a clear desk policy and all the rest. In fact he suffered from OCD. A bona fide nutcase. He couldn't stand any clutter at all. There were a load of Racal stat muxes, which the immediate need for had passed. He hired a skip (dumpster) and filled it with all sorts of things which didn't need to be thrown away. The stat muxes were on top. Someone saw them and his eyes popped out. He rescued them and sold them for £700 within a few days. This was 35 years ago, so in modern money, a lot more. They sometimes had to buy new items after he'd decided to throw out perfectly good ones.

That's it exactly, frustrating, wasteful and silly, just as you said. Unfortunately, when I saw the row of Audio Precisions on the shelf suddenly disappear, I suspected what happened but it was the conversation about investigating this one problem a couple of weeks later that confirmed it.

The first scope I got was a work write-off that the manager who hired me authorized a take-home on when one of the parts room was being relocated. Actually, we had a laugh because this scope was waiting for me on my bench when I got in and at first I thought I'd gotten in trouble with the IT department because I had been bidding on a Tektronix 475 on eBay the shift before, and I first thought it was a dig at me for doing that. The two of us had a good laugh at how that coincidence worked out and ended up shooting the breeze about eBay bidding strategy; the 475 had some intermittent button issues so I was willing to put a low bid in and take some risk but happily let it go when it sold for a lot more and let someone else take their chances on it.

Starting with the first of a couple of subsequent managers since then, it's been similar with the clear desk policies, down to crappy Teknion office desks replacing the benches pretty early on, routine purges of the parts and equipment rooms have left the place sparse. The theory circulating out there the last few years is that management wants the shop to look like an IT support desk. The purge orders came down from upper management and extended to pretty much all locations. I remember being sent to one site and seeing the room full of vintage Tektronix and HP gear waiting for the e-waste contractor. This was right at the same time I bought my house and started building my own workshop and I remember staring thinking if I could load some of this equipment waiting for the e-waste company to come scrap it into my car, I'd have a well equipped workshop literally overnight. Even the drill press couldn't escape this.

Several years later, some of that plant's facilities were being refreshed and the engineering department sent a project manager plus several installers out to that site overlapping several weeks of me working there. All of a sudden, in that building's maintenance shop, a brand new drill press showed up on one of the benches next to an outlet that had it's own dedicated circuit. The engineer said something about how great this outlet was, perfectly located for this drill press he'd just bought and I told him the reason for that was, it was the dedicated power point for the drill press that used to be there that they'd thrown out in that big purge a couple years before. We were all groaning about how you can't make this stuff up.

just went thru the same thing with my A/C. icing due to a slow refrigerant leak that they have been trying to find for about 4 years.

used to cost me $65 a pound for R410. but according to the maintenance manager at my local A/C shop, the government just mandated that R410 must be replaced with a more environmentally friendly refrigerant and can no longer be produced.

so the 2 lbs they put into my system cost me $195 each. holy crap! almost 400 bucks for a top up! (and they still can't find the leak).

looks like it will mean a total system replacement. am trying to delay this because according to the manager new systems are still shipping with the obsolete R410 and units with the new chemical will not be available until oct or nov. wtf?

I've been hearing that R-410A has been getting more expensive from that friend of mine who is in HVAC. We both went to college together and he ended up in the trade after a couple of career changes. Loss of refrigerant is what we both suspected at first until we put his gauges on and found out it's still fully charged. It turns out that it's the TX valve so we're going to change that after I get home from work today. It sounds like finding leaks can be a royal pain and I know at least one of the local companies here won't attempt to do that pushes for wholesale replacement of everything.

Hopefully your system can hang on another six to eight weeks for the cooling season to wind down so you can get a new-refrigerant system once they become available later this year. It would be horrible to install a new R-410A central air system now, now that R-410A itself is discontinued and rising in price and have the full service life of the equipment still ahead of it.

What we came up with for my central air is to only run it while I'm home so it doesn't run unattended in case anything bad happens, and turn it off leaving the blower fan on only while I'm at work. When I got home last night after work and visiting my parents, I switched the air back on and decided that since we'd been discussing the possibility the system's not working efficiently with the bad TX valve, this might be a good time to get out the Fluke 52 thermometer I picked up during the winter since this is the perfect application for a dual channel thermometer that can do a T2-T1 calculation:







This is the temperature spread I'd been told I should expect and the central air ran fine last night and I was able to get a good, if short sleep before heading back into work this morning.

[Zenith]

These are nothing without the calibration certificate, since they are calibrators themselves. Not sure where you would go to get this calibrated; probably NPL or PTB in Germany. PTB have been known to turn up at Makerfaires and allow you to connect your stuff to their equipment. I took a voltage source and measured it with an HP3458 that they had calibrated the day before Not sure they would allow you to do a full calibration of this though, even if I could carry it there

Mine is the kind of thing that only very serious metrology labs would have, the best available until Josephson Junctions came along. 4.5 digit calibrators are mere toys by comparison.

I have a sinking feeling that you are slipping into volt nuttery. Fight it or it will end in ruin.